I want to write an algorithm to calculate the number of syllables in a word. This process is an automated one that will be run on an entire dictionary so manually counting the number of breaths, chin movements etc. as mentioned in other questions won't scale. I also don't want to visit a website like howmanysyllables to input the word because I don't want to depend on a non free and open source system.

To get around tricky words like "Wednesday", I thought it would be easier to use the IPA transcription of words instead. I have the IPA transcription for all words in my downloaded dictionary but to my dismay I discovered there seems to be no surefire method of counting syllables.

Consider these two transcriptions to IPA:

pronunciation: pɹəˌnʌn.siˈeɪ.ʃən
conscientious: ˌkɒnʃiˈɛnʃəs

For the IPA word "pronunciation", lower apostrophe, upper apostrophe and period can be used to tell where the syllable breaks occur. The IPA word for "conscientious" only seems to strictly indicate a single break. You could say the "ʃ" indicates a syllable break but I worry this isn't the case for all words.

Is there a list of rules that define syllable breaks in US English for IPA transcriptions?

  • 1
    You're not going to be able to find rules for splitting syllables. You will need to find a different set of IPA transcriptions. Dictionaries like Dictionary.com use IPA and mark all the syllables with a combo of stress marks + spaces. You may not be able to find an IPA list/API for free, so maybe you should consider using a different transcription system.
    – Laurel
    Commented Jun 4, 2017 at 20:58
  • That's disheartening. I'm new to this area but I thought this would have been a solved problem. Thanks for the heads up. Commented Jun 4, 2017 at 21:02
  • 3
    Bear in mind that some words have a different number of syllables for different speakers.
    – oerkelens
    Commented Jun 4, 2017 at 21:18
  • 1
    Thanks to everyone for their helpful comments. I think I'll do done more research before tackling this problem, the complexity of which I seem to have underestimated. Commented Jun 5, 2017 at 10:37
  • 1
    In the end I did use the CMU dictionary. One syllable for each vowel phone in a word. Commented Apr 27, 2018 at 8:09

1 Answer 1


Here's a spreadsheet with English words, IPA and syllable data https://docs.google.com/spreadsheets/d/1EfFhhC7kcTzB8c2UhAC53txRiTLKl3R9C2AM7ee0AVM/edit#gid=104606017

So after coming across this question and wanting to know the answer myself, I managed to pull together a few different sources of information into one Excel spreadsheet, and get data for just over 31,000 words with both their IPA pronunciations, and the number of syllables. I also found some frequency data, which can be used to naively split the words into deciles, according to how often the words are roughly used - meaning that you can sort the words by both syllable length and frequency of use (which is a very rough measure of complexity.)

Caveat: the pronunciation data I've pulled is from UK English. I pulled it from a GitHub repo containing IPA information for many languages, which also contains a file containing US English words and their pronunciations, linked here.

I haven't integrated it myself because I only need the UK data*, but you can pull the data into Excel fairly easily - the fields are split by whitespace, so Text-to-columns should separate the IPA from words. If you're comfortable with Excel then it should be fairly simple to combine this with the other data to get a list of all US English pronunciations and their syllable counts.

The rest of the sources for the data are linked in the spreadsheet itself.

* Also, I did try to add in the US Word data to the Google Sheets, but Sheets complained that this would exceed the cell limit. I put together this project based on UK data before I realised that you're probably from the US, and built all the formulas around it, so it would take a bit of unpicking for me to switch it over fully. I might come back to it another day. Hope this is still of some use to you.

  • I don't know how to use it, but can you find the number of syllables in 'hour' and 'power' (British English)? Commented Sep 25, 2020 at 17:16
  • Sure, just go to the "Words - All" spreadsheet and search for the term you're interested in. It looks like "hour" is classed as one syllable and "power" as two syllables. Which I think makes sense, as "power" starts a second syllable with the /w/ onset, whereas "hour" just has a triphthong vowel nucleus.
    – Lou
    Commented Sep 25, 2020 at 17:19
  • Interesting. Do you pronounce 'hour' with one syllable or two? Commented Sep 25, 2020 at 17:20
  • See my edited comment, but yeah I would pronounce power with two syllables usually.
    – Lou
    Commented Sep 25, 2020 at 17:20

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